DE2134153B2 - METHOD OF MANUFACTURING A SOLID PHOSPHORIC ACID CATALYST - Google Patents

Description

The invention relates to a method for producing a solid phosphoric acid catalyst by mixing a diatomaceous earth with a phosphoric oxygen acid at elevated temperature in a quantitative ratio, that the mixture obtained 60 to 80 percent by weight of phosphoric acid and 40 to Contains 20 weight percent diatomaceous earth. Shaping the mixture obtained in this way into molded articles, Treating the shaped body with steam at a temperature of 260 to 427 ° C and drying the with Steam treated catalyst in dry air at a temperature of 288 to 454 ° C

Solid phosphoric acid catalysts, particularly olefin polymerization catalysts, are in practice usually prepared by mixing a solid adsorbent with a phosphoric acid, Extruding the mixture and drying and calcining the resulting extrudate particles. at the production of such catalysts has been shown that a treatment of the catalyst particles in a steam atmosphere is very advantageous with regard to the catalyst activity. However, the to a steam treatment to be attributed advantages at least partially eliminated by a considerable reduction in the compressive strength of the particles. Particles of low compressive strength tend to Crumbling, so that considerable abrasion losses occur in handling and reactors in operation or associated facilities can become clogged.

There is also a method of the type specified for the preparation of phosphoric acid and silicophosphoric acid-containing polymerization catalysts by mixing powdered kieselguhr with phosphoric acid, shaping the mixture thus obtained into shaped pieces and calcining the shaped pieces (DT-AS 10 46 598), in which As a special treatment, a high pressure is exerted on the mixture of diatomite and phosphoric acid to be worked up into shaped pieces until this mass has assumed a vitreous appearance. The pressure applied to the mixture of diatomaceous earth and phosphoric acid should usually be at least 10 kg per cm ² and preferably 15 kg per cm ² or more, and the printing treatment is advantageously at elevated temperature, however, not be carried out above 150 ⁰ C.. According to the details of this known method, no work measures should be applied there that would lead to the formation of a plastic mass, e.g. B. a kneading.

Accordingly, a processing comes the diatomaceous earth-phosphorus-oxygen acid mixture into moldings by known particularly simple and therefore advantageous measure of extrusion can not be considered contrary, the vitreous mass formed in the special pressure treatment is first heated for several hours at 150 to 220 ⁰ C to the while the reaction of phosphoric acid with kieselguhr to remove all or part of the water formed, and then the mass is z. B. formed by pressing into tablets or by cutting or granulating into pieces or grains of the desired size. The measures of high-pressure treatment, the heating of the vitreous mass for several hours and the shaping of the material obtained by granulating or pressing into tablets require additional operations involving equipment and operational expenditure. Furthermore, the processed into moldings catalyst by heating for several hours at high temperatures, for example 5 hours at 35O ⁰ C in a dry air stream, in the known method is calcined. According to the details given there, a treatment at 200 to 300 ^° C. with steam, obviously pure steam, is carried out for several hours after the calcination, e.g. B. 16 hours with steam at 260 ⁰ C. The catalyst is then dried at a temperature of, for example, etv / a 300 ⁰ C by briefly, z. B. 15 minutes, treated with a dry gas stream, such as air, and then cooled.

Overall, the known method thus requires quite a number of, in some cases, comparatively expensive and long work steps.

The invention is accordingly based on the object of providing a method of the type specified at the outset Manufacture of a solid phosphoric acid catalyst for hydrocarbon conversion to create the does without complex and lengthy procedural measures, can be carried out easily and safely and still leads to a solid phosphoric acid catalyst which has good activity, especially for the Olefin polymerization, and has good compressive strength.

The invention relates to a method for producing a solid phosphoric acid catalyst by mixing a diatomaceous earth with a phosphoric oxygen acid at an elevated temperature in a quantitative ratio that the mixture obtained 60 to 80 percent by weight of phosphoric acid and Contains 40 to 20 percent by weight of diatomaceous earth, shaping the mixture thus obtained into moldings, Treating the molded body with steam at a temperature of 260 to 427 ° C and drying the steam-treated catalyst in dry air at a temperature of 288 to 454 ° C, which is characterized in that the mixture is heated to 38 to 260 ° C, shaped by extrusion and the molded bodies obtained in this way, without prior calcination, initially for 0.5 to 1.5 hours in one

Water vapor air atmosphere containing 20 to 30 percent by weight of HzO and then dried in dry air for 0.5 to 1.5 hours.

The method of the invention is as shown in FIGS the above information is readily apparent easy to do. A special high pressure treatment comparable to the above known method not necessary. The mixture prepared from the starting components can be used at elevated temperature by the known very simple and therefore advantageous measure of extrusion to the desired moldings are molded. A multi-hour heating treatment prior to molding, as in the known method outlined above, is not necessary. Also one several hours of calcination, as in the known method before the treatment of the catalyst with There is no need for steam. After the extrusion, the specified two-stage drying treatment is sufficient first in an atmosphere containing water vapor and then in dry air. These two Drying treatments only need 0.5 to 1.5 hours each. B. 16 hour treatment with There is no need for water vapor, as in the above known method. Any complex and lengthy ones Work steps are not required at all; on the contrary, fewer and simpler ones are sufficient overall measures to be carried out for the manufacture of the catalyst. Nevertheless, this has a high and for the application in practice has far sufficient compressive strength and good activity.

In a particularly preferred embodiment of the method of the invention, diatomaceous earth is mixed with a polyphosphoric acid to form a mixture of the specified composition. The mixture is heated to a temperature of 38 to 260 ° C. and then extruded, whereupon the extrudate particles, without prior calcination, first in a steam atmosphere containing 20 to 30 percent by weight of H2O for 0.5 to 1.5 hours at a temperature of 343 to 399 ° C and then dried in dry air over a period of 0.5 to 1.5 hours at a temperature of 371-427 ⁰ C.

Further aspects and embodiments of the invention emerge from the following in greater detail Explanation.

The main component of the solid catalyst is a phosphoric acid, preferably a phosphoric acid, in which the phosphorus has a valence of +5. The acid makes up 60 to 80 percent by weight of the final catalytic converter. Orthophosphoric acid (H3PO4) and pyrophosphoric acid (H4P2O7) are used preferred, primarily because of their cheapness and easy accessibility. Other phosphoric acids however, can also be used.

When using orthophosphoric acid, it can be used in different concentrations, from about 75 to 100% or even acid that contains free phosphorus pentoxide. The ortho acid can contain pyroic acid, corresponding to the primary phase of dehydration of the orthophosphoric acid. Within these concentration ranges, the acids are liquids of different viscosities that easily mix with diatomaceous earth. In practice it has been found that pyrophosphoric acid (H4P2O7) may well be combined with diatomaceous earth at temperatures somewhat above its melting point of 61 ⁰ C.

Triphosphoric acid (HsPsOio) can also be used. The catalysts can also consist of a diatomaceous earth and phosphoric acid mixtures, the orthophosphoric acid, Pyrophosphoric acid, triphosphoric acid and others Polyphosphoric acids can be prepared.

Another phosphoric acid that can be used is tetraphosphoric acid of the general formula H6P4O13. she results when three molecules of water are removed from four molecules of orthophosphoric acid (H3PO4). It can be produced by gradual and controlled dehydration by heating orthophosphoric acid or pyrophosphoric acid or by adding phosphorus pentoxide to these acids in corresponding quantities. When using the latter procedure, phosphoric anhydride is used gradually added until it is 520% by weight of the total water present. After standing At ambient temperatures, crystals of tetraphosphoric acid separate from the viscous one Liquid out. It can also be the crude tetraphosphoric acid mixture, without crystallization, with the diatomaceous earth be mixed.

The carrier material consists of a diatomaceous earth, i. H. a material made of predominantly silicic acid or silicon dioxide-like character.

The diatomaceous earth is mixed with the phosphoric oxygen acid, ie orthophosphoric acid, pyrophosphoric acid, triphosphoric acid or tetraphosphoric acid, expediently at a temperature of 38 to 260 ^° C., preferably 93 to 260 ^° C. The result is a slightly moist to almost dry mass, which becomes sufficiently plastic when pressed to allow proper extrusion and cutting.

The extrudate particles are then first in a water vapor atmosphere, without prior calcination, which contains 20 to 30 percent by weight of water vapor, 0.5 to 1.5 hours at a temperature of 260 to 427 ° C, preferably 343 to 399 ° C, and then in dry air for 0.5 to 1.5 hours at one temperature from 288 to 454 ° C, preferably 371 to 427 ° C. '**

The catalyst is primarily suitable for the polymerization of olefinic hydrocarbons, especially for the polymerization of light olefinic hydrocarbons under normal conditions liquid hydrocarbons, such as for use as gasoline components.

The catalyst can be used both when carrying out operations in the vapor phase and when carrying out operations in the liquid phase. In the polymerization of olefins which are gaseous under normal conditions, the catalyst particles are usually introduced into a vertical cylindrical reactor and the olefin-containing gas mixture is passed through it at a temperature of 177 to 288 ° C. and a pressure of 7.8 to 103 atm. Such conditions are particularly useful when processing olefin-containing materials, e.g. B. reflux fractions of a debutanizing column containing 10 to 50% or more propylene and butylenes. When processing mixtures which essentially consist of propylene and butylenes, the catalyst can be used under conditions which favor maximum utilization of both normal and isobutylene, ie a temperature of 121 to 163 ^° C. and a pressure of 35 to 103 Atm.

As further areas of application for the catalyst

may be mentioned: the alkylation of cyclic compounds with olefins, the cyclic compounds being in particular aromatics, polycyclic compounds, Naphthenes and phenols come into consideration; Condensation reactions, e.g. B. as between ethers and Aromatics, alcohols and aromatics occur rather than phenols and aldehydes; Reactions in which one Hydrohalogenation of unsaturated organic compounds occurs; Isomerizations; Ester formations by reactions of carbocyclic acids and olefins.

When using the catalyst for vapor phase polymerizations and other vapor phase reactions, it is often advantageous to have small amounts of moisture add to avoid excessive dehydration of the catalyst with subsequent reduction in the Avoid activity. Water or steam can be added to the reactor charge z. B. in a crowd 0.1 to 6 percent by volume can be added.

Example 1 (comparative example)

A solid phosphoric acid catalyst was prepared by mixing diatomaceous earth with it Polyphosphoric acid (86.17% P2O5), which had previously been heated to 171 ° C. The diatomaceous earth was mixed with the acid in a weight ratio of 1: 2. The resulting hot powdery Mass was extruded and the wet extrudate particles were dried for 70 minutes at 371 ° C. with air containing 30% water vapor. The hot gases were guided in the upward direction through the extrudate particles, the latter were distributed in a Conveyor arranged with running belt. The compressive strength of the catalyst particles was 9.9 kg. the Compressive strength was determined with an apparatus which allowed it, continuously and with more uniform Increase in force exerted on the particles, starting with a load of NuIL The specified Compressive strength is the arithmetic mean of the force that was required to give each particle a given Crush number of individual particles.

The catalyst thus prepared was placed in the form of a fixed bed in a vertical tubular reactor and a light hydrocarbon feed containing 37% olefins in the form of propylene was passed in an upward flow through the catalyst bed. The hourly space velocity of the gas was 0.2. the pressure was 69 atm. and the temperature was 204 ⁰ C. It was a 76prozentige converting propylene to propylene polymer in this mode obtained with a single pass.

Example 2 (invention)

A solid phosphoric acid catalyst was prepared in exactly the same manner as in Example 1 with the Exception that the steam-dried product continues in one for the treatment of individual batches formed oven was dried in dry air at 399 ° C. for 70 minutes. The compressive strength of the Catalyst particles averaged 16.6 kg versus 9.9 kg in the previous comparative example. Under the same conditions as in the preceding comparative example, the catalyst prepared in accordance with the invention had a 78 percent conversion of propylene to propylene polymer achieved.

The reasons for the sudden improvement in compressive strength achieved without impairing the activity, are not yet known in detail.

Claims (1)

Claim: A method of manufacturing a solid phosphoric acid catalyst by mixing a diatomaceous earth with a phosphoric acid elevated temperature in such a proportion that the mixture obtained is 60 to 80 percent by weight Contains phosphoric acid and 40 to 20 percent by weight diatomaceous earth. Molding the mixture obtained in this way to form moldings, treating the moldings with steam a temperature of 260 to 427 ° C and drying the steam-treated catalyst in dry air at a temperature of 288 to 454 ° C, characterized in that the Mixture heated to 38 to 260 ° C, shaped by extrusion and the moldings obtained without prior calcination, initially 0.5 to 1.5 hours in a 20 to 30 percent by weight H2O containing water vapor atmosphere and then dried in dry air for 0.5 to 1.5 hours will.